The disclosed embodiments of the present invention relate to filtering out/reducing unwanted signal components present in a signal input, and more particularly, to a signal processing circuit having mixer units using oscillation signals with different phases (e.g., opposite phases) and a frequency-selective combining block for frequency-selectively combining outputs of the mixer units and related method thereof.
In general, a wireless communication receiver is required to have the capability of detecting weak signals in the desired frequency band. Specifically, the wireless communication receiver is required to detect in-band signals in the presence of very strong interference signals such as out-of-band (OOB) blocker signals. The most common solution to solving problems caused by very strong blocker signals is to use very high quality factor (Q) bandpass filters at the front-end of the wireless communication receiver. For example, surface acoustic wave (SAW) filters may be employed to offer the desired attenuation of OOB blocker signals. However, using SAW filters leads to significantly increased cost and circuit board area.
Thus, there is a need for an innovative design which can effectively attenuate or eliminate the unwanted signal components (e.g., OOB blocker signals) by using a simple circuit architecture.